Torpedo launching mechanism



Dec. 11, 1945. s, ER gr 2,390,635 I TORPEDQ LAUNCHING MECHANISM FiledJan. 12, 1942 2 Sheets-Sheet 1 ec-v11, 1945. s. N. BARKER ETAL 2,390,635

-TORPEDO LAUNCHING MECHANISM Filed Jan. 12, 1942 2 Sheets-Sheet 2.

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Patented Dec. 11, 1945 UNITED STATES PATENT OFFICE 2,390,635 TORPEDOLAUNCHIN G MECHANISM of Great Britain Application January 12, 1942,Serial No. 426,406

' In Great Britain May 14, 1940 9 Claims.

The present invention relates to the launching of marine torpedoes bygas pressure generated by combustion of a smokeless powder propellentcharge in a combustion-chamber which is separate from but communicateswith a torpedo-tube in such a manner that the gases pass into thetorpedo-tube from it.

The pressure required in a torpedo-tube to launch the torpedo is only afew atmospheres, and at pressures below about 20 atmospheres smokelesspowders do not burn satisfactorily, but generate excessive quantities ofnitrous gases.

According to the present invention, for launching a torpedo in themanner described, there is provided the combination with thetorpedo-tube, of a separate combustion-chamber having apressure-reducing connection therewith constituted by a permanently openbut restricted aperture, and a propellent charge which comprises afast-burning portion and a slow-burning portion so proportioned that thefast-burning portion rapidly builds up an adequate pressure in thecombustionchamber, and the slow-burning portion maintains an adequatepressure during the discharge of the torpedo.

It desirable to keep the weight of the combustion chamber and of thetorpedo-tube as low as possible but it will be appreciated that if afast burning charge were employed alone a light construction would notbe possflole owing to the high peak pressures which would be developed.Furthermore the high peak pressure in the torpedotube would be liable tocollapse the tail of the torpedo. On the other hand if a slow burningcharge were employed alone this would result in the production of highlycorrosive gases owing to the inefficient combustion and it would beincapable of producing a sufficiently high pressure in the timeavailable to launch the torpedo satisfactorily. The employment of both afast burning and a slow burning charge of the kind hereinafter describedto a large extent solves the abov problems.

It is found desirable in practice that the pressure in the torpedo-tubeshould rise to its maximum value as rapidly as possible, this valuebeing of the, order of to 10 atmospheres, and this is achieved by therapid production of a suitably high pressure in the combustion-chamber,which highpressure is reduced by the pressure-reducing orifice. Theadequate pressure to be produced by the fast-burning portion of thecharge is therefore one which is adequate for the two purposes of (a)producing the desired maximum initial pressure in the torpedo-tube, and(b) producing the. higher pressure in the combustion-chamber which isnecessary for effective combustion of the remainder of the charge asabove mentioned, whilst that produced by the slow-burning portion issuch as will give in the torpedo-tube the pressure required to continueand complete the effective discharge of the torpedo.

According to another feature of this invention, the propellent charge iscontained in a casing which ofiers no effective resistance to theemergence of the combustion gases into the combustion-chamber.

Another feature of this invention relates to the composition of thepropellant charge used in the apparatus above-mentioned, and accordingto this feature of the invention, the quantity of the fastburnin-gportion of the propellent charge is such as to provide rapidly themaximum pressure in the torpedo-tube to effect the discharge of thetorpedo. The actual amount will depend primarily upon the sizes of thecombustion-chamher and the restricted aperture and the safe workingpressure in the combustion chamber and to a smaller extent on the deadspace in the torpedotube. The amount and the rate of burning of the slowburning charge and the size of the restricted aperture are so corelatedas to permit a predetermined maximum pressure to be built up in thecombustion-chamber which is required for ensuring sufficient gas to passinto the torpedo-tube to launch the torpedo at the desired velocity.Preferably, the fast-burning portion of the charge is in the form ofcords (hereinafter referred to by the reference character 36) which areof considerably smaller web-thickness than the slowburning portion whichis preferably in the form of rectangular strips or tubes (hereinafterreferred to by the reference character 36a )which ar long in relation totheir other dimensions and have a form characterized by aconstant-burning surface. The term "web-thickness means the leastdimension of the fast-burning or the slow-burning portion of thecartridge charge. In the tubular l form, this is the thickness of thewall of the tube; and in the cord form, it is the diameter of the cord.

The propellent charge is assembled in a cartridge of usual constructionand according to another feature of the invention, the quantity of theslow-burning portion is from three and a half to five times the weightof the fast-burning portion. As hereinafter described in detail, thefastburning portion of the charge is so arranged with reference to theslow-burning portion of the charge that the flame from the fast-burningportion spreads over the inside and outside surfaces of the slow-burningportion and therefore ignites it over substantially the whole of itssurface. Ac-

cording to another feature of the invention, the

cartridge-case is open ended and its closure is efiected by a Celluloidor like combustible disc,

whereby there is no effective resistance oifered to the emergence of thegases from the cartridge- 7 Figure 2 is a section to an enlarged scaleon the line 2-2 of Figure 1;

Figure3 is a section also 'to an enlarged scale on the line 3-3 ofFigure 1, and

Figures 4 to 9 are indicator. diagrams showing variation of pressure inthe combustion-chamber andf torpedo-tube during" the burning of thecharge.

The combustion-chamber comprises a main cy lindrical body portion I t!hemispherical at one end H and closed at the other end by a breechblockl2, and breech IS. The breech-block operates according to the well knowninterruptedthread princip e and slides into the open position along twoguide rails 14, one being secured at each side of the chamber.

at; its open endby a Celluloid disc H. The cartridge-case I5 is heldbetween the breech-block I2. and the'breech I3 by means of a splitcartridge holder l8 facilitating the removal of the cartridge-case afterfiringg The base of the cartridge is fitted with a primer l9 which maybe either an ordinary percussion primer or an electric primer"containing a resistance heating element, or a primer adapted for eitherpercussion or electric firing.

V The firing mechanism is adapted for both pereussion and electricfiring and to this end comprises a firing pin mountedin the breech-blockby means of insulating bushes 2|. 2!! is electrically connected byflexible conductors 22 to the central electrodes 23 of one or moreterminals 24 to which suitably armoured cables from the firingcontrolmay be connected. For percussion firing a pistol bolt 25, provided withan insulated striker head 26, is driven towards the firing pin by apistol-spring 21. Normalli, the pistol-bolt is retained in its retractedposition by a transverse release pin 28, the latter being pulled out forfiring. Greasing nipples 29 are provided for the lubrication of themoving parts.

The combustion-chamber is adiacent and connected directly to thetorpedo-tube 30 at a point nearits rear end by a Venturi nozzle 3!, theentrance to thelatter being protected by a grid 32. having perforationsabout in diameter. The throat portion 33 of the nozzle is madeseparately from the main body portion so that it can be readilyexchanged to provide larger or smaller nozzle openings according torequirements. The nozzle 3| is attached bybolts (not shown) to suitablefacings provided on the combustion-chamber and torpedo-tuberespectively, packing Inem bers l34, 35 being inserted to ensure agas-tight joint. Thus the combustion chamber is in direct Acartridge-case l5 contains the propellent charge [6 and is closed Thefiring pin together with .55 lb. of a slow-burning composicommunicationwith the torpedo tube through a permanently open but restrictedaperture.

A safety release device 45 is screwed into the hemispherical end of thecombustion-chamber and comprises a bursting disc 31 and a protectingdisc of asbestos 38 clamped between the screwthreaded members 39 and 40.

In putting this invention into efiect it must be borne in mind that theweight and dimension of charge used will vary with the size of thetorpedo, and with the degree of gas-tightness achieved between thetorpedo and the wall of the torpedotube. The optimum size of the Venturinozzle will also vary according to the weight of charge used.

By way of example, in the particular case when it is required to launcha 1570 lb. torpedo of 17.7 inches diameter from a torpedo-tube in whichit has an effective travel of 13 feet, the empty combustion-chamber mayhave a capacity of about 325 cubic inches, its weight, exclusive of thebreech and firing mechanism being 25 lbs. The throat diameter of theVenturi nozzle is .49 inch.

The propellent charge in the cartridge 15 consists in this particularcase of .107 lb. of a fastburning composition comprising nitro-glycerine4.1%, nitrocellulose 50%, diethyl diphenyl urea 9% in the form of cordsof diameter .047 inch,

tion comprising nitroglycerine 35.5%, nitrocellulose 51.5%, diethyldiphenyl urea 4.75%, diamyl phthalate 7%, mineral jelly 0.25% andpotassium nitrate 1%, in the form of tubes each about 6.7

7 inches long and about .137 inch web-thickness.

As will be apparent from Figs. 1 and 3, the cords of fast-burningcomposition are arranged in parallel to form a core 36 and are alsoarranged so that they encircle the slow-burning tubes 36a which are madeof the slow-burning composition, the said tubes being grouped around thefastburning core which extends from one end to the other end of saidtubes. The purpose of this arrangement is to insure that the flame fromthe fast-burning cords will spread over the length i of the slow-burningtubes and thus ignite them throughout substantially the whole length oftheir inside and outside surfaces. In this way accidental influences onthe ignition of the slow-burning charge consisting of the tubes 36a arereduced,

' and consistency of results is improved. Furthermore, the transversearrangement ofv portions of the cords 35 around the tubes 36a serves theuseful function of keeping the whole charge together as a unit.

The small size powder is inserted as a core 36 (see Figure 3) betweenthe tubes 36a and also wrapped around them and the whole charge isloaded in a brass cartridge-case l5 of which the open end'is closedwitha Celluloid disc I! and in the base of which a primer I9 issituated.

When fired, the cartridge builds up a maximum chamber pressure of 102atmospheres which is maintained for about /6 sec., and gives a maximumpressure of about 5 atmospheres in the torpedo-tube. and ejects thetorpedo satisfactorily within approximately half a second from the firingof the cartridge.

A method of launching during a second period, and during both: saidperiods allowing such quantity of the gas generated to pass into thetube as will build up a a torpedo from a tube consists in generating gasat a high rate during a first period so as to build up a pressure ofthe. order of a to atmospheres, then reducing; the rate of generation tomaintain Said pressure maximum pressure of the order of to atmospheresduring the discharge of the torpedo.

The following is a description with reference to. Figures 4 to 9 showinghow the variation in the weight of the slow and fast burning charges andthe diameter of the nozzle affects the pressures built up in thecombustion chamber and in the torpedo-tube. The ordinates in thesediagrams represent the pressures and the abscissae repre. sent time. Theexperiments were carried out in connection with apparatus having thedimensions above referred to and having a torpedo of the size and weightas set out above and having a length of 18 feet.

Figures 4, 6 and 8 represent the conditions set up in the combustionchamber while Figures 5, 7

and 9 represent the conditions set up in the tor-W pedo-tube.

In Figures 4 and 5 the diameter of the nozzle employed was .45 inch ineach of the experiments and the weight of the fast burning charge was 48grams in each case. The curves show the effect of varying the weight ofthe slow burning charge. The curves 50, 5| and 52 represent theconditions produced by employing 200 grams, 120 grams, and 180 gramsrespectively of the slow burning charge. The maximum pressures obtainedin the combustion chamber by these charges were 1625, 850 and 1.300pounds per square inch respectively, and in the torpedo tube 65 lbs., 53and 70 pounds per square inch respectively.

In each diagram there is an initial phase of low, almost constantpressure during which the priming charge is igniting the fast and slowburning powders. 1y at a rate which is determined by the size of thecombustion chamber and nozzle and by the surface area of the charge, andhence, for a given size of chamber and nozzle to a considerable extentby the weight of the fast burning portion since this latter has arelatively large surface area in proportion to its weight compared withthe slow burning powder. When all the fast burning powder has beenconsumed the slope of the curve decreases and then remains substantiallyconstant for a further phase at a value determined by the size of thenozzle and the surface area of the slow burning powder. When all thepowder has been consumed the pressure falls away approximatelyexponentially. Other things being equal, the duration of the third phasewould be proportional to the weight of the slow burning portion of thecharge, but in the experiments in question it was not possible to varythe die size of the slow burning powder, so that variations of theweight of the slow burning powder also produced variations in the rateof burning of the charge as a whole owing to the variations in surfacearea.

Experiment 52 shows a desirable form of combustion-chamber curve withthe pressure well maintained. Increasing the weight of slow burningpowder as in experiment 50 results in the pressure rising to a peak atthe end of the third phase, while reducing the weight of slow burningpowder as in experiment 5| has the opposite effect, both beingdisadvantageous from the point of view that the combustion-chamber mustbe made stronger and therefore heavier, in proportion to the meaneffective pressure. Figures 6 and 7 show the curve 50 compared with a,curve 53 obtained by increasing the diameter of the nozzle to .5 inch.The weight of the charges of the slow and fast burning material beingthe same as in experiment 50. This resulted in the maxi The pressurethen rises rapidmum pressure in the combustion chamber being reduced to1200 pounds per square inch, but the maximum pressure in the torpedotubes was increased to 73 pounds per square inch.

The weight of charges used in experiment shown by curve 5! would besuitable for use with a nozzle of smaller diameter, if under theseconditions sufficient gas were pr'oduced to launch the torpedosatisfactorily. Alternatively. better results might be obtained by usingslow burning powder of smaller web size i. e., by increasing the rate ofburning of this portion of the charge. It would not be suitable in thiscase to attempt to obtain a level topped diagram by reducing the weightof the fast burning portion since this would reduce the pressure belowthat necessary to ensure efiicient combustion.

The diagrams set out in Figures 8 and 9 show the eifect of varying theweight of the fast burning charge while keeping the nozzle size'and theweight of the slow burning charge constant. In this instance thediameter of the nozzle was .35 inch and the weight of the slow burningcharge was 130 grams. The weight of the fast burning charge employed forthe curve 54 was 4.8 grams and for the curve 55 was grams. The formerresulted in the production of a combustion chamber pressure of 1500pounds per square inch and the latter 1300 while the maximum torpedotube pressure for the first charge was 56.5 lbs. per square inch, andthe torpedo tube pressure for the second charge was lbs. per squareinch. In the case of the experiment shown by curve the charge containedtoo little fast burning powder resulting in a comparatively slow rate ofpressure rise during the second stage and a low pressure at the end ofthis stage. Experiment shown by curve 54 indicated that by increasingthe fast burning charge from 30 to 48 grams resulted in averyconsiderable improvement.

Amongst the advantages obtained according to our invention are the factsthat the combustionchamber may be of lighter construction than thehitherto known combustion-chambers for torpedofiring charges and that anintermediate gas receiver is not required, whilst all uncertainty aboutthe action of a valve between the firing chamber and the torpedo-tube isavoided, and the lag before the torpedo commences to move is reduced,and accuracy of aim is increased. Moreover, the cooling eifect on thegases in the combustion-chamber is diminished, and consequently, theamount of propellent powder required is reduced.

We claim:

l. A torpedo launching cartridge comprising a casing containing a fastburning charge in the form of cord about .047 inch in diameter andcomprising 41% nitroglycerine, 50% nitrocellulose. 9% diethyl diphenylurea and a slow burning charge in the form of tubes about 6.7 incheslongand having a web-thickness of about .137 inch, which tubes comprise35.5% nitrcglycerine, 5.5% nitrocellulose, 4.75% diphenylurea, 7% diamylphthalate, 25% mineral jelly, and 1% potassium nitrate, the weight ofwhich slow burning charge is from three and a half to five times theweight of the fast burning charge.

2. A method of launching a torpedo from a tube to which through aconstricted opening is connected a combustion chamber which consists ingenerating gas in said combustion chamber by the combustion of a chargeat a high rate during a first period so as to build up a pressure of theorder of a to atmospheres, and then by connected a combustion chamber,which consists in generating gas in said combustion chamber by thecombustion of a charge formed from smokeless powder, which combustion isarranged to take place at a high rate during a first period so" as tobuild up a pressure of the order of 100 to 150 atmospheres, and then bythe combustion of a slow-burning charge, formed from smokeless powder,thereby reducing the rate of generation of the gas in said combustionchamber to maintain said pressure during a, second period, and duringboth said periods allowing such quantity of gas generated in' saidcombustion chamber to passthrough the constricted opening into the tubeas will build up a maximum pressure of the order of 5 to atmospheresduring the discharge of the torpedo.

4. A torpedo launching cartridge comprising a casing having therein afast-burning portion of the charge in the form of cords arranged inparallel to form a core, a slow burning portion of the charge in theform of tubes grouped around said fast-burning core so that the coreextends from one end to the other end of the tubes, and a furtherfast-burning portion of the charge in the form of a cord encircling thetubes transversely from one end to the other end thereof.

5. A torpedo launching cartridge comprising a casing having therein afast-burning portion of the charge in the form of cords about 0.047 inchin diameter and arranged in parallel to form a core, a slow-burningportion of the charge in the form of tubes about 6.7 inches long andhaving a web thickness of about 0.0137 inch grouped around saidfast-burning core so that the core extends from one end to the other ofthe tubes, and a further fast-burning portion of the charge in the formof a cord encircling the tubes transversely from one end to the otherend thereof and having the same diameter as the first of said cords;

6. A torpedo launching cartridge comprising a casing having therein afast-burning portion of the charge in the form of cords composed ofnitro-glycerine, nitro-cellulose, diethyl diphenyl urea, said cordsbeing arranged in parallel to form a core, a slow-burning portion of thecharge in the form of tubes composed of nitro-glycerine andnitro-cellulose diphenyl urea, diamyl phthalate, mineral jelly andpotassium nitrate, which tubes are grouped around the cords so that thecords extend from one end to the other end of Said tubes, and a furtherfast-burning portion of the charge in the form of a cord encircling thetubes-transversely from one end thereof to the other and of the samesize and composition as the first of said cords.

7. A torpedo launching cartridge comprising a casing having therein afast-burning portion of the charge in the form of cords arrangedparallel to form a core, which charge contains about 41% nitro-glycerineand about nitro-cellulose, a slow-burning portion of the charge in theform of tubes grouped around said fast-burning charge so that the cordsextend from one end to the other end of the tubes, which tubes includeabout 35.5% nitro-glycerine and about nitro-cellulose, and a furtherfast-burning portion of the charge in the form of a cord encircling thetubes transversely from one end thereof to the other and of the samesize and'composition as the first of said cords.

8. A torpedo launching cartridge comprising a casing,' acharge in thecasing having a fastburning portion of the charge in the form ofsmokeless powder fashioned into cords arranged parallel with one anotherto form a core, a slowburning portion of the charge fashioned fromsmokeless powder to form tubes, which tubes are grouped around the poreso that the cords extend from one end to the other end of the tubes, anda further fast-burning portion of the charge in the form of a cordencircling the tubes transversely from one end to the other end thereofand of the same size and composition as the first of said cords.

9. A torpedo launching cartridge comprising a casing containing afast-burning portion of the charge in the form of cords of about 0.047inch smallest transverse dimension and packed together to form a core,the composition of which cords is mainly nitro-glycerine andnitro-cellulose in the proportion of about 4 to 5, a slow-burningportion of the charge comprising a plurality of tubes each about 0.137inch smallest transverse dimension grouped around said core and of alength substantially equal to the greatest di-" mension of the packedcords and composed mainly of nitro-glycerine and nitro-cellulose in theproportion of about 3 /2 to 5, a further fast-burn ing portion of thecharge in the form of a cord encircling the tubes transversely from oneend to the other end thereof and of the same transverse dimension andcomposition as the first of said cords, which fast-burning portion ofthe charges comprise from about 20 to 28%% of the total.

STUART NETHERVVOOD BARKER.

GEORGE SIDNEY SELMAN.

VICTOR GEORGE BULL.

VIVIAN CHARLES ERIC MARTEN-GWILLIAM. ROBERT WARK. THOMAS THOMSON.

